Kramers' law is a formula for the spectral distribution of X-rays produced by an electron hitting a solid target. The formula concerns only bremsstrahlung radiation, not the element specific characteristic radiation. It is named after its discoverer, the Dutch physicist Hendrik Anthony Kramers[1].
The formula for Kramers' law is usually given as the distribution of intensity vs. the wavelength of the emitted radiation:[2]
The constant K is proportional to the atomic number of the target element.